Coating apparatus



June 10, 1941 w. F. THIELE ETAL 2,244,859

COATING APPARATUS Originalv Filed May 1l, 1936 2 Sheets-Sheet l June 10, 1941. w. F. THIELE Erm.

COATING APPARATUS 2 .Sheets-Sheet 2 Original Filed May 11, 1936 Patented June 10, 1941 UNITED STATES PATENT OFFICE COATING APPARATUS Forest, Ill.

Original application May 11, 1936, Serial No. 79,048. Divided and this application January 20, 1939, Serial No. 251,987

4 Claims.

This application is a division of our co-pending application Serial No. 79,048, led May 11, 1936.

This invention relates to an improved paper coating method and apparatus, and refers specifically to a method of coating relatively thin or tissue paper made on a so-called Yankee paper machine, the coating operation comprising one of a plurality of continuous steps in the manufacure of the paper.

Yankee paper machines are primarily designed for producing light weight papers known to the trade as tissues. Such machines have but one dryer, which is in the form of a drum, usually ten or twelve feet in diameter, short forming wires, a limited number of presses and a limited drying capacity. Cooperating top and bottom felts are employed for transferring the paper web from the Fourdrinier wire to the dryer.

Heretofore, great diillculty has been experienced in producing opaque papers of light weight on Yankee paper machines. Due to the shortness of the forming wire and the thinness of the sheet oi' paper usually made on this type of machine little success has been had in obtaining a desired degree of opacity of the paper web by loading the paper with materials such as clay, titanium oxide, zinc oxide, satin white, and like materials. The addition of clay vor similar opacity producing material to the web as it is formed on the wire of the machine causes the top pick-up felt to become filled very `quickly with the Inaterial so added making it necessary to shut down the paper machine and wash the top felt at frequent intervals.

Our invention contemplates the application of a relatively thick paste-like material, comprising one or more minerals and one or more aclhesives, or a combination of them, to the web of paper after it has been transferred to the dryer of the paper machine by the top pick-up felt, the

coating materials being squeezed into the depressions of the adjacent side'of the web of paper which would normally be rough, thereby producing the opacity desired. However, although our invention is capable of applying relatively thick or heavy materials to the paper, which coating processes heretofore proposed have been unable to use, it is to be understood that we do not wish to be limited to this specific type of material since our process is capable of use with thinner or more liquid coating or other web surface modifying materials.

The utility, objects and advantages of our invention will be more apparent from the accompanying drawings and `following detail description.

In the drawings:

Fig. 1 is a fragmentary diagrammatic side elevational view of suitable apparatus for carrying out our process.

Fig. 2 is a detail side elevational view of the coating mechanism per se.

Referring in detail to the drawings, I indicates a portion of the frame of a paper machine of the Yankee type, which may be supported by a plurality of columns 2 one only of which is shown in the drawings. The frame I supports oppositely positioned bearings 3, one of which is shown, and in which a shaft 4 is journalled, said shaft carrying drying drum 5.

In the Yankee type of paper machine, which is particularly adaptable for making light weight or tissue paper, but one drying drum is used which, however, is oi relatively large diameter, in the neighborhood of I0 or I2 feet. A canopy or hood 6 encompasses a large portion of the periphery of the drum 5, said hood comprising a conduit 'I for discharging air, usually hot air, into contact with the paper web carried upon the surface oi the drum. The drum 5, of course, is usually heated by means of steam which is carried in the interior thereof.

Thepaper web is formed upon a relatively short forming wire (not shown) and upon being stripped therefrom is carried between two felts 8 and k9, being the upper and lower felts respectively. 'I'he felts, of course, assist in the removal of moisture from the web oi' paper by capillary attraction, this removal being facilitated by passing the felts and interposed web between one or more presses ID comprising osculating rolls II. After passage through the last press I 0. the web is stripped from the lower felt 9 which returns to the wet end ci' the machine over guide roll I2, said web being carried upon the upper felt 8 over a couch roll I3 which osculates with drum 5. At t'ie point of osculation between couch roll I3 and drum 5, the web is stripped from the felt '8 and transferred directly to the heated external surface of the drum, while felt 8, returns to the wet end of the machine. During passage of the web over the drum I5 the surface in contact therewith becomes smooth and finished, while the other surface of the web is subjected to the contact of the hot air delivered from the conduit 1, the web of paper being relatively thin is substantially dry when it is stripped from the drum and passed around roll I4, the web being designated I5. After passage around the roll I4 the web may be cut into sheets, or reeled as a continuous web.

Paper made in the manner, and upon a machine, as has been hereinbefore described, is very thin and consequently tends to be translucent. If the attempt is made to fill the paper with clay or the like during formation of the web to render the same more opaque, diillculty is encountered in that the upper felt is quickly'filled and necessitates shutting down the machine to wash the felt. This manifestly, is very objectionable from the standpoint of economy and also because the speed of production of the paper web, is materially reduced.

Our invention contemplates the coating of the paper web I5 after it has been transferred to the dryer drum, that is, after the web has left the felts 8 and 9. Consequently, neither of fthe felts will be exposed to contact with the coating material and therefore will not become filled, thus obviating the necessity of stopping the machine.

The following described apparatus has been found suitable for carrying out our invention in conjunction with the Yankee paper machine hereinbefore described. A frame I6 is supported by means of straps I1 from the main frame I, as may be seen in Fig. 1. Mounted on frame I6, are a plurality of transversely extending rolls I8, I9, 20 and 2| which are disposed, during normal operation, in serially contiguous relationship. Roll I8 engages and extends transversely across the path of travel of the paper web I5, during the initial portion of its movement around the dryer 5. Said roll is slightly shorter in length than the width of the web or the width of the drum 5, so that the coating material applied by roll I8, does not come in contact with the outer surface of the dryer drum 5.. Roll I8 is journalled in oppositely disposed bearings 22 which yare in turn carried by blocks 23. Frame I6 on each side of thel machine .comprises members 24, 25 and 26, members 24 being spaced from members 25 and 26, to form ways for the blocks 23 which are slidablyl positioned between the members 24 and 25. A channel 21 is secured at the end of frame I6 to members 24 and 25 and serves as a spacing means for said members.

In carrying out our process, roll I8 is disposed in contact with the web I5 upon drum 5 immediately adjacent the point where said web has been stripped from the upper felt 8. As will be hereinafter more fully described, roll I8 is adapted to carry a lm of coating material or other modifying material upon its surface which is transferred to the surface of the web of paper. A capstan screw 28 is threaded in the web of channel 21, the head of said screw, during normal operation, serves as a stop against which block 23 abuts, and thereby controls the degree of proximity of the surface of the roll I8 to the web I5, upon the dryer drum surface. It can readily be seen that inasmuch as roll I8 is shorter than the width of web I5, there is no danger of depositing coating material on the highly finished surface of the drum which may be destructive to said surface.

Shaft 29 carries roll I9 and is journalled in oppositely disposed bearings (not shown) which are carried on opposite sides of the machine in blocks 30. A guide 3I serves to connect members 25 and 26, said guide being respectively connected at each end to said members. Blocks 30 are Icarried between members 24 and guides 3I and are slidable a limited distance longitudinally of the frame I6. Consequently, roll I9 is movable toward and away from roll I8. A capstan screw 32 is threadedly positioned in block 23 and the head thereof provides a stop against which the block 30 may abut to limit the degree of proximity of roll I9 to roll I8. A screw 33 is threadedly positioned in block 30, the shank of said screw passing freely through an aperture 34 provided in block 23 and serves to control the degree of separation of blocks 23 and 38 and hence rolls I8 and I9.

A worm pinion (not shown) is mounted upon the shaft 29 and is adapted to mesh with a worm wheel (not shown) mounted upon shaft 35 within housing 36. Eccentric mechanisms 31 are associated with shaft 35, said eccentric mechanisms being ultimately anchored to block 30. This mechanism is of conventional type, having heretofore been widely used and comprises no part, per se, of our present invention. The purpose of the mechanism is to oscillate roll 30 axially simultaneously with its rotation.

Roll 20 is journalled in opposite bearings 38 carried by blocks 39 which are slidably disposed in ways comprising members 24 and 26. A capstan screw 40 is threadedly secured to block 30 and its head is adapted to provide a stop against which the block 39 abuts to control the degree of proximity of rolls I9 and 20. A screw 4I is also threadedly engaged in block 30, the shank of which passes freely through aperture 42 provided in block 39 whereby the maximum separation or spacing of blocks 30 and 39 and hence rolls I9 and 20 may be adjustably controlled.

Roll 2| is journalled in opposite bearings 43 carried by blocks 44 which are slidably disposed in the ways comprising members 24 and'26. A

capstan screw 45 ls threadedly secured to block 39 and its head is adapted to serve as a stop against which the blocks 44 abut to control the degree of proximity of rolls 2l) and 2I. vA bolt 46 having a head 41 and nut 48 is loosely positioned through apertures 49 and 50 provided in blocks 39 and 44, respectively and serves to adjustably control the spacing of blocks 39 and 44 and hence rolls 20 and 2l.

A cylinder 5I (Fig. 1) is mounted at the end of frame I and carries a piston (not shown) the piston rod 5Ia projecting from the cylinder and being connected to block 44. The purpose of the cylinder-piston mechanism is to slidably move blocks 23, 30, 39 and 44 to the right or left along members 24, 25 and 26. It can readily be seen that when fluid under pressure, preferably air, is introduced into cylinder 5I on one side of the piston, rod 5Ia will tend to move said blocks along the axis of the rod. If, for instance, the piston rod moves to the right, as viewed in Fig. 2, block 44 will move to the right thereby separating rolls 20 and 2I until the head 41 andnut 48 abut blocks 39 and 44 respectively. Blocks 39 and 44 will then move in unison, drawing roll 20 away from roll I9 until the head of screw 4I contacts block 39. Block 30 will then move in unison with blocks 39 and 44 thereby moving roll I9 away from roll I8 until the head of screw 33 contacts block 23, at which the time block 23 will be moved with the remaining blocks thereby separating roll I8 from the web I5 on the drum 5. Of course, when the rolls are thus separated, the device is rendered inoperative as a coating agency.

A roll 52 is carried by shaft 53 which in turn is journalled at its ends in bearings 54 slidably mounted in standards 55, which are mounted on the opposite blocks 30 and consequently are stationary with respect to the axial motion of the roll I9 and roll 52 is hence stationary with respect to said axial movement. However, roll 52 rests of its own weight upon roll I9 and is rotated thereby. The purpose of the arrangement will be hereinafter more fully described.

The upper adjacent portions of rolls 20 and 2| form a longitudinally extending upwardly open trough which is completed at each end by a dam 51, preferably of frictionless material, forming a receptacle for a puddle of coating material which is to be supplied to the paper web I5. As above mentioned the coating material that we have found suitable for carrying out our invention is in the form of a relatively thick paste-like material, and for rendering the thin web of paper opaque we employ a compound and one or more adhesives, or a combination thereof. It is to be understood that this invention is not to be limited to the use of minerals such as clay, calcium carbonate, titanium oxide, zinc oxide and satin white and adhesives such as casein, starch, glue and the like for rendering the paper opaque, because manifestly this invention may be used for applying any usable substance for modifying the surface of the web of paper. Heretofore coating materials have only been used in dilute solutions. By virtue of our invention we have now found it possible to employ paste-like coating material wherein the consistency thereof is at least 10% solids, a'nd may be as high as 60%. 'I'he surface of the paper thus coated for rendering it opaque also acquires an excellent finish which renders it particularly suitable for printing thereon.

Roll I8, may be driven by means of belts, gears, motors or directly from the dryer drum 5, so that the peripheral speed of said roll and the drum are the same, and roll I9, may also be driven in a manner similar to roll I8. Roll 20 is preferably driven by means covering a wide variable range of speeds. While roll 2I`, is preferably driven by a separate motor having a speed range from 1 R. P. M. to a peripheral speed equal to the peripheral speed of rolls I8 and I9, the purposes of which will hereinafter appear. Roll 52 may be driven from the same power source as roll I9, since their peripheral surfaces desirably travel at the same rate of speed.

In operation, the screws 28, 32, 33, 40, 4I, 45 and 'bolt 46 are first adjusted so that the adjacent rolls may be separated at desired amounts. The coating material is then deposited in the upwardly open trough formed by the rolls 2lil and 2I and dams 5'I, and the web of paper I5, started through the machine in the usual manner. Then the rolls I8, I9, 20, 2| and 52 are broughtup to the desired speeds, at which time compressed air is admitted to the cylinder 5I, which through the connections above described, pushes the rolls to the left. with respect to the position indicated in the drawings, for disposing the rolls in a ldesired relation to each other, and with the roll I8 engaging the web of paper I5, trained around the dryer drum 5. It will now be clear that as rolls 20 and 2| rotate a quantity of coating material in the form of a film will adhere to the surface of roll 2U, which is transferred to the surface of roll I9, and which in turn transfers the film of coating material to the roll I8 for applying it to the outer surface of the web of paper which is trained around the dryer 5. The roll 52, positioned above the roll I 9, which rotates and reciprocates, causes the coating material to be uniformly and smoothly distributed over the surface of roll I9, from which it is. picked upv by roll Il for applying it to the web of paper. The roll Il, is preferably positioned relatively to the paper web so that the coating material is squeezed into the depressions of the adjacent surface of the paper web, producing the opaque effect desired. By virtue of the character of coating material that may ybe employed and the novel arrangement of apparatus for applying it, the coating operation becomes one of aseries of continuous steps for producing coated paper and we are able to obtain excellent results, wherein the finished web of paper is uniformly opaque, and is free from skips,l ridges and the usual effects. It will be manifest, however, that the coating material selected may be for purposes other than for rendering the paper opaque, and we do not wish to be understood as limiting our invention to the specific use herein disclosed, which is merely i1- lustrative of this invention.

We claim as our invention:

1. A coating device for coating paper while the same is travelling over the surface of the single drying drum of a Yankee type paper machine comprising opposite supporting frames disposed adjacent said drying drum, a plurality of bearings slidably disposed in alignment upon said frames, rolls carried by said bearings, means for applying coating material to one of said rolls, means for slidably moving said bearings toward each other to transfer vsaid coating material from said `roll to the remaining rolls, the last roll in alignment being in contact with the web upon the drying drum whereby coating material is applied to said web.

2. A coating device for coating paper while the same is travelling over the surface of the single drying drum of a Yankee type paper machine comprising opposite supporting frames disposed adjacent to the point on said drying drum where the web to be dried initially contacts said drum, a plurality of bearings disposed in alignment upon said frames, rolls carried by said bearings, means for applying coating material to one of said rolls,

. means for moving said bearings toward each other to transferv said coating material from said roll to the remaining rolls, the last roll in alignment Vbeing in contact with the web upon the drying drum while said web is still damp whereby coating material is applied to said web, and means carried by said bearings tc control the degree of contiguity of said rolls.

3. A coating device for coating paper while the same is travelling over the surface of the single drying drum of a Yankee type paper machine comprising opposite supporting frames disposed adjacent said drying drum, a plurality of bearings slidably disposed in said frames adjacent said drying drum, rolls carried by said bearings, means for applying coating material to one of said rolls, means for sliding said bearings toward each other to bring said rolls in contacting relationship whereby to transfer said coating material from said roll to the remaining rolls, the last roll in alignment being in contact with the web upon the drying drum whereby coating material is applied to said web while said web is still damp, means carried by said bearings to control the degree of contiguity of said rolls and means for slidably separating said bearings and rolls from each other.

4. A coating device for coating paper while the same is travelling over thesurface of the single drying drum of a Yankee type paper machine comprising opposite supporting frames disposed whereby coating material is applied to said web,

' means carried by said bearings to control the degree of contiguity of said rolls, means for separating said bearings and rolls from each other, and means carried by said bearings for controlling the maximum degree of separation of said bearings and rolls with respect to each other.

WILLIAM F. THIELE. HOWARD BREWSTER RICHMOND. 

